Surface-ocean pH has declined from 8.2 to 8.1 over the industrial era due to the growth of atmospheric CO 2 concentrations. This decline corresponds to a 30 % change in oceanic acidity.
Observed reductions in surface-water pH are nearly identical across the global ocean and throughout Europe’s seas.
Ocean acidification in recent decades is occurring a hundred times faster than during past natural events over the last 55 million years.
Ocean acidification already reaches into the deep ocean, particularly in the high latitudes.
Average surface-water pH is projected to decline further to 7.7 or 7.8 by the year 2100, depending on future CO 2 emissions. This decline represents a 100 to 150 % increase in acidity.
Ocean acidification may affect many marine organisms within the next 20 years and could alter marine ecosystems and fisheries.

Surface-ocean pH has declined from 8.2 to below 8.1 over the industrial era due to the growth of atmospheric CO 2 concentrations. This decline corresponds to an increase in oceanic acidity of 26%.
Observed reductions in surface-water pH are nearly identical across the global ocean and throughout Europe’s seas.
Ocean acidification in recent decades is occurring a hundred times faster than during past natural events over the last 55 million years.
Ocean acidification already reaches into the deep ocean, particularly in the high latitudes.
Models consistently project further ocean acidification worldwide. Surface ocean pH is projected to decrease to values between 8.05 and 7.75 by the end of 21 st century depending on future CO 2 emission levels. The largest projected decline represents more than a doubling in acidity.
Ocean acidification may affect many marine organisms within the next 20 years and could alter marine ecosystems and fisheries.